Photoelectric musical instrument



Dec. 18, 1956 Filed. Nov. 23, 1951 w. D. HARBAUGH 2,774,272

PHOTOELECTRIC MUSICAL INSTRUMENT 4 Sheets-Sheet 1 22 I I I E i L 5-3 1 1 126; 76 1 g 5 ".23 i MOIOR I -1 I x I d Dec, 38, 1956 W. D. HARBAUGH 2,774,272

PHOTOELECTRIG MUSICAL INSTRUMENT Filed Nov. 23, 1951 4 Sheets-Sheet 2 Dec. 18, 1956 w. D. HARBAUGH 2,774,272

PHOTOELECTRIC MUSICAL INSTRUMENT Filed Nov. 25, 1951 4 Sheets-Sheet 4 United rates atent C PHOTOELECTRIC MUSICAL INSTRUMENT Watson D. Harbaugh, Evanston, Ill.

Application November 23, 1951, Serial No. 257,731

14 Claims. (Cl. 841.18)

This invention relates to an organ as a musical instrument and more particularly to a system for generating complex sound waves throughout the musical ranges including the notes and mixtures of tones of any one or more of a plurality of diiferent devices by which man has made music including the voice.

Prior attempts have been made to duplicate the tonal qualities of the organ or other music producing devices without the use of the bulky and expensive apparatus which is inherent in pipe organs and other devices. These attempts utilize either electrically vibrated reeds or electronic oscillators, the outputs of which are combined in various proportions in an endeavor to produce the desired note or tonal chord. However, these existing devices do not accurately reproduce the tones of the organ but, having fallen short of their objective, have attained status in the musical arts as additional instruments possessed of certain distinctive qualities peculiar to them.

Also, all attempts in the past have failed to produce a single instrument which is capable of accurately reproducing all the notes or" the musical scale of the large variety of instruments normally present in a symphony orchestra. In particular, existing devices are not able to produce or vary the tapered tone of a struck piano string or a plucked or bowed string such as a violin. Furthermore, no augmentation in volume of any notes above other notes in a keyboard has been attained in existing devices.

Accordingly, one object of this invention is to provide a simple instrument which will accurately reproduce the tones of a pipe organ without the expense and bulk inherent therein.

Another object of this invention is to provide a single musical instrument which will produce the tapered tone and vary the taper of a vibrating string such as a piano string.

A further object of this invention is to provide a simple musical instrument which is capable of reproducing all the notes of the musical ranges of any musical instrument with fidelity and accuracy.

Another object is to provide an instrument which is capable of producing either the tapered tone of a piano or the abrupt sustained tones of an organ.

A further object of the invention resides in providing a musical keyboard instrument wherein the musician can infinitely vary the relative volume of individual tones or notes being sounded simultaneously even during sustained simultaneity.

In accordance with these and other objects, one embodiment of the invention comprises a plurality of cylinders having sound tracks constituting indicia or information representative of each of the notes of the musical range of the instruments whose tones are to be reproduced. The cylinder is rotated at a desired speed, and light from an electric lamp within the cylinder passes through the moving tracks as beams of light whose intensities are thereby varied to provide undulating beams of light representing tones or notes to be reproduced.

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The undulating light beams pass through scanning slits to impinge upon a plurality of shutters. Preferably, there is a shutter for each track and each shutter can be moved independently of the others. The shutters gradually vary from an uppermost opaque portion to a lowermost transparent portion so that when the shutters are raised, the undulating light beams may pass therethrough to impinge upon a plurality of photoelectric cells which generate electric signals in response to the undulation in light intensity produced by the tracks. Because of the gradually varying light transmissivity of the shutter, depending upon the distance the shutter is raised, the electrical signals may be gradually increased or decreased in amplitude as the shutters are raised and lowered. The electrical signals are amplified and coupled to an electro-acoustical transducer to produce the desired sound wave for audition. The shutters are raised and lowered either electrically or manually in accordance with the various embodiments of the invention.

In another embodiment of the invention, all beams of undulating light are focused upon a single reflecting surface to produce a composite light beam resultant of the undulating and varying intensities of the plurality of incident light beams, which composite beam is subsequently focused upon a single photoelectric cell.

Also, the invention may utilize a cylinder with a plurality of films thereon having indicia representative of a single musical note in the range of each of the instruments, the tones of which are to be reproduced. In this embodiment if the cylinders have identical tone tracks the cylinders are rotated at different speeds in the ratio of the difi'erent notes in the musical scale so that all the notes of said scale are reproduced by the plurality of rotating cylinders.

Another embodiment utilizes a mechanical apparatus for variably controlled progressive movement of the shutter relative to the beam of light to produce the tone taper and which is capable of operating either with or without the tone taper characteristics.

Many other objects and advantages of the invention will become apparent from a consideration of the following description and claims when taken in conjunction with the drawings wherein;

Fig. l is a schematic view of an electric organ wherein a keyboard electrically controls the reproduction of tapered tones;

Fig. 2 is a plan view of a light-actuated note-reproducing means utilizing the electrical control keyboard;

Fig. 3 is a side view of the note reproducing means of Fig. 2;

Fig. 4 is a schematic view of an electric organ having a manual control keyboard;

Fig. 5 is a plan viewof a pair of light energized note reproducers utilizing the manual keyboard;

Fig. 6 is a side view of the note reproducing means of Fig. 5.

Fig. 7 is a plan view of a means for optically combining the individually produced light beams to form a composite light wave representation of a musical sound including the notes of the individual beams;

Fig. 8 is a schematic diagram of a circuit for electronically combining the voltage waves representative of a plurality of musical notes to produce a composite musical sound;

Fig. 9 is a sectional view of a film bearing cylinder and electric lamp for producing light variations representative of a plurality of musical notes;

Fig. 10 is a chart showing a gearing arrangement for rotating cylinders having identical films of a single note in a predetermined gear ratio to produce a plurality of notes of different and evenly tempered intervals.

Fig. 11 is a side elevational view of a modification of the manual keyboard for producing tapered tones; and

Fig. 12 is a perspective View of foot pedal controls for the manual keyboard modification of Fig. 11.

Referring now to the drawings wherein like reference numerals indicate the same elements throughout the several views, and more particularly to Fig. l of the drawings, each of a plurality of musical note reproducing units 20, 21, 22, 23, 24, 25 and 26 generate all the notes produced by the desired number of instruments in evenly tempered intervals in predetermined octaves. In the illustrative modification shown, the lower three octaves 20, 21 and 22 are shown to include the interval notes of only three instruments having notes within those three octave ranges whereas the upperfour octave units 23, 24, 25 and 26 are shown to include the interval notes of four instruments to the extent their ranges come within these octaves and three of these instruments may be the same as those of the lower three octaves. The desired instru ments in thhe plurality of reproducer units 20 to 26, inclusive, are selected by a plurality of switches 27, 28, 29 and 3t operation of which grounds conductors 31, 32, 33 and 34, respectively. Operation of the switches 27 to St), inclusive, or any permutation thereof grounds the associated conductors so that a subsequent application of voltage to a plurality of control elements within the units 20 to 26, inclusive, operates said elements to produce the desired notes.

The determination of the'notes to be played by the predetermined instruments is controlled by a conventional keyboard 35 having a plurality of manually operated'keys 36. Each of the keys 36 is secured to one of a plurality of switches 37 so that voltage from a grounded battery 38 is applied through a conductor 39, the switches 37 and a plurality of conductors 4i? to the units 26 to 26, inclusive. For convenience, the diagram of Fig. 1 only shows the direct connection of the switch 37 to units 20 and 26. Conductor cables 50, 51, 52, 53 and 54 interconnect the units 21, 22, 23, 24, and 25, respectively, with arrangements of keys 36 and switches 37 similar to those shown. Operation of any key 36 or combination of keys closes the associated switch or switches 37 to connect battery 38 to control elements within the reproducing units 20 to 26, inclusive, to energize and operate those control elements which had previously been conditioned for operation by manual operation of certain of the switches 27 to 30, inclusive.

Each of the units 20 to 26, inclusive, comprises a plurality of cylinders 55 (Figs. 2, 3, 5, 6, and 9) equal in number to the number of notes'in an octave. Each cylinder 55 is composed of alternate light opaque bands 56 and transparent slots 57 (Figs. 2 and 9). A film 58 bearing indicia of a predetermined musical sound is secured in each of the slots 57. Each cylinder 55 has secured thereon the film 58 representing the same musical note asproduced by the difierent desired musical instruments. As shown in Figs. 2 and 9, each of the cylinders 55 carry four films 58 representing the same note as produced by four different instruments, for instance, a piano, tuba, clarinet and violin. The cylinder 55 in the octave units 20 to 22, inclusive, would only carry three films 58 representing the notes of the three instruments reproduced by these particular units. Obviously, the cylinder 55 can be adapted to carry any number of films 58 depending upon the number of musical instruments, the notes of which are to be reproduced.

The films 58 are produced. by any of the methods well known in thearts so that each film 58 will vary the intensity of the light passing therethrough in accordance with the complex sound wave representing a note produced by a particular musical instrument. By recording each note of each instrument individually, it is possibleto obtain a perfect note so that the reproduction of the system is free from any possibility of error and is also of the highest fidelity.

The cylinder 55 (Fig. 9) is provided with two hollow projecting portions 59 and 60 which are rotatably journalled within two fixed standards 61. A cold cathode tube 62 is rigidly secured within the cylinder 55 by two resilient dielectric washers 63 which engage the inner periphery of the projecting portions 59, 60, and the outer periphery of dielectric caps 64 on each end of tube 62. A cold cathode tube is found particularly useful since the light emission therefrom remains substantially constant and free from deleterious flickering. The tube is energized from a source of direct current power 65 through a pair of conductors 66 and 67, a pair of spring leaf contacts 68 and 69, and then through a pair of conductive pins 70 and 71 which are insulated from the cylinder 55 by a pair of dielectric grommets 72 and 73 to the contacts of the tube 62. A plug 74 closes one end of cylinder 55 and is removable to permit replacement of the tube 62.

A spur gear 75 formed on the outer extremity of projecting portion 59 is driven by a constant speed motor 76 (Fig. 1) and suitable mechanical linkage so that all of the plurality of cylinders 55 rotate the films thereon at the same speed at which the films 58 were produced. The cylinders 55 are positioned closely adjacent a plurality of plates 77 (Figs. 2, 3, 5 and 6) having scanning slits 78 therein so that upon rotation of the cylinders 55 by the motor 76 a plurality of light beams pass from the tubes 62 through the films 58 and slits 78 to impinge upon a plurality of shutters 79. Due to the movement of the films 58 past the slits 78, the plurality of light beams are varied in intensity in accordance with the indicia on the moving film'58 representing the various musical notes.

Each of the shutters '79 is interposed between one of the slits 78 and one of a plurality of photoelectric cells 80. The shutters 79 are tapered from top to bottom as viewed in Figs. 3 and 6 so that an opaque portion normally intercepts the light beam from the slits 78. The shutters 79 are tapered in their light transmission characteristics from this uppermost opaque portion to a lowermost portion which is transparent. Accordingly, movement of the shutter 79 will increase or decrease the magnitude of the light intensity variations applied to the cells 80. This movement can be rapid or gradual. Rapid movement gives a sustained tone while gradual movement varies the light energy applied to the cells 80 to produce a tapered tone such as that of a plucked or bowed string in a piano or violin. In Fig. 3 the movement provided is a rapid movement.

Each of the shutters 79 is secured to an arm which is pivotally mounted on a rod 91. A spring 92 secured to the arm 99 holds it against a stop bar 93 so that the opaque portion of the shutter 79 normally intercepts the light from the slits 78. A soft iron slug 94 is pivotally mounted on one end of the arm 90 so as to be positioned above the core of a solenoid 95. Energization of the solenoid 95 attracts the slug 94 and moves the arm 90 in a counterclockwise direction to raise the shutter 79 so that light variations passing through the slit 78 impinges upon the cell 80 in full magnitude. A release of solenoid 95 permits the spring 92 to return the arm 90 to its normal position intercepting the beam of light.

The plurality of solenoids 95 are selectively conditioned for operation by closing any desired permutation of the switches 27 to 30 (Figs. 1 and 2) inclusive, to ground their associated conductors 31 to 34, respectively, where: by a predetermined number of the solenoids 95 have one side of their operating windings grounded in accordance with'the selection of the instruments whose notes are to be reproduced. The other side of the operating windings of the solenoids 95 is connected 'to switches 37 through the common conductor 39. Therefore, manual operation of any of the keys 36 (Figs. 1 and 2) closes the associated switch 37 so that the conditioned solenoids 95 are energized through a circuit from grounded battery 38 through conductor 39, switch 37, conductor 40, windiug of solenoid 95, selected conductor 31 to 34, inclusive,

to the operated switches of the plurality of switches 27 to 30, inclusive, and therethrough to ground. Furthermore, each set of tones may be placed under control of stops similar to those in an organ, and several notes may be played by a single key when corresponding stops are out. With such an arrangement each stop would control a switch connected in series with all the switches of the notes under the control of that stop as further described hereafter in connection with Fig. 2.

Operation of the solenoids 95 permits light beams varying in intensity in accordance with the indicia on the film 58 to impinge upon the cells 80. The cells 80 (Figs. 3 and 8) produce electrical currents varying in amplitude in accordance with the variation of light intensity received. These varying currents are conducted from the cells 80 through amplifier 96, a plurality of conductors 97 (Fig. 8) to a plurality of mixer-amplifiers 98 wherein the individual notes of the various instruments are mixed and coupled into an electro-acoustical transducer 99 to produce an audible sound representative of the plurality of simultaneously reproduced notes.

The second modification of the invention as shown in Figures 4, 5, and 6 is one wherein each plurality of octave note reproducer units 160 to 166, inclusive, include stops or conditioning elements for preparing each unit for reproduction of the musical notes of a selected number of instruments. Each of the conditioning elements is connected to a grounded battery 197 through a conductor 108. The conditioning elements are also connected to a plurality of conductors 1119, 11%}, 111, and 112 which are electrically grounded by operation of switches 113, 114, 115, 116, to operate the selected elements. After the units 100 to 106, inclusive, are conditioned to reproduce only the notes of the selected musical instruments, manual operation of any combination of keys 117 in the conventional keyboard 35 will produce only the tones of the selected notes produced by the preselected instruments.

Each of the units 100 to 1416, inclusive, includes the same means for producing the light variations representative of the musical notes of the various instruments as in Figs. 1, 2, and 3. However, the shutter 79 is secured to an arm 118 which is pivotally secured to a shaft 119. A spring 129 secured to the arm 11% holds it in contact with a stop bar 139 so that the opaque portion of the shutter 79 is in alignment with slit 78. A solenoid 131 may be secured to the upper surface of arm 118 and is positioned directly below and against a soft iron slug 132 which is pivotally mounted on a fingered plate 133. One finger of plate 133 is positioned above each of the solenoids 131 associated with a particular cylinder 55. A projecting portion 134 of the plate 133 which is pivotally mounted on a shaft 135 engages one end of a pivotally mounted lever arm 136. The other end of the arm engages the pivoted key 117 which is held by a spring 137 against a stop bar 133 until depressed.

Energization of one or any combination of the relays 131 by closing one or any combination of the switches 113 to 116, inclusive, holds the related iron slug 132 in contact with the core of the solenoid 131 where it is held to move with the slug until the energization is removed from the selected solenoid 131. Manual depression of one of the keys 117 thereafter pivots the lever 136 and the plate 133 whereby the shutter 79 and arms 113 magnetically coupled with the plate are raised to energize the photo-electric cells 3% with undulating beams. The resultant varying electric currents produced by the cells 80 are amplified and mixed by the circuit shown in Fig. 8 as described above. With this arrangement a varying of the distance through which the key is fingerpressed will vary the volume of that note so that it is possible for a musician to modulate each note or all notes in varying degrees for heretofore unknown musical effects.

The system shown in Figs. 1 to 6, inclusive, may be further modified by utilizing only a single film 58 for the entire musical scale of each of the instruments, the

notes of which are to be reproduced. In this modification each of the slots 57 in the cylinders 55 related to a particular instrument hold the same film 58 and the cylinders 55 are rotated at different speeds in accordance with the gearing and speed ratios shown in the chart and gearing diagram of Fig. 10 where conventional antibacklash gears are used. The variations in speed are such that the single note recorded on the film 58 produced variations in light intensity on the cells which are representative of the desired notes. The entire gearing arrangement, of which only one octave is shown in Fig. 10, is driven from the same constant speed motor 76 utilized in the basic system. Gearing arrangements other than that described could be used to produce the desired different notes but this one gives greatest fidelity on the evenly tempered scale.

In another modification, the separate light beams of varying intensity representative of the different notes are optically combined to produce a composite light beam representative of the plurality of individual light beams. In Fig. 7, four sources of light beams are positioned a-djacent to the periphery of a chamber 140 having a curved reflecting surface 141 of such configuration as to reflect the composite light beam on the single photoelectric cell 80. The varying electric current produced by the cell 80 is representative of the light beams from the four sources and, accordingly, is representative of the desired composite sound. The electrical current is subsequently amplified and converted into sound energy by an electroacoustical transducer 99.

Figs. 11 and 12 show a mechanical system for raising and lowering the shutters 79 and for also providing by a foot pedal control either a loud or soft volume for sustained or variably tapered tones. An arm is pivotally mounted at 150a on a conventional piano or organ key 151 which in turn is pivotally mounted at 151a. A striker bar 152 is pivotally mounted in a bifurcation 153 in the arm 150 and is resiliently urged outwardly by a spring 154. When the key 151 is depressed, the arm 150 is moved upwardly so that the bar 152 momentarily engages the end 155 of an arm 156 pivoted at 15611 to rotate said arm in a clockwise direction against the action of a compression spring 149. This rotation moves a push rod 157, pivotally secured to arm 156 at 157a, in a downward direction to raise the shutter 79 carried by a pivoted lever arm 158 which is pivotally secured to arm 157 at 158a,

The original counter-clockwise rotation of key 151 when struck permits a folower arm 159 to rotate about a shaft 160 in a clockwise direction. This rotation of arm 159 lowers a toothed arm 161, which is pivoted to arm 156, into engagement with a gear 162 by means of a link 163.

The gear 162 is driven at a variable predetermined speed in a counter-clockwise direction so that upon engagement of the toothed arm 161 with the gear 162, these two elements move together in a counter-clockwise direction to lower the shutter 79 at a predetermined speed. This movement of the shutter 79 gradually decreases the magnitude of the light intensity variation passed through the tapered shutter 79 and accordingly produces a tone of gradually tapered intensity. This tone taper is stopped either by releasing the depressed key 151 so that it strikes and pivot the arm 159 in a counter-clockwise direction to raise the arm 161 out of engagement, or by permitting the gear 162 and toothed arm 161 to remain in engagement until the arm 156 reaches its normal position at which time the teeth on arm 161 will ride over the teeth on the gear 162.

A spring 164 and an adjustable arm 165 provide a means for returning key 151 to its normal position against a stop member 166 when the key is released and also provides a touch control whereby the musician can adjust the resistivity of the keys 151 to motion. A stop arrears bar" 167 cooperates with compression spring 149 to hold thearm 156 in a normal position.

The length of time during which each tone produced is tapered is also controlled by a foot pedal including a foot pedal lever 170 which is pivoted about shaft 171 (Fig. 11 and 12). An arm 172 interconnects the shaft 160 with the lever 170 so that counter-clockwise rotation of lever 179 upon depression of the foot pedal connected thereto moves the arm 172 downwardly and along with it the shaft 169. Since one end of the arm 159 (Fig. 11) rests against a frame, 173 to which a pivoted link 174 connected to the shaft 160 is also secured, downward movement of arm 172 lowers shaft 160 and accordingly pivots arm 159 about its left end as shown in Fig. 11.

This movement of arm 159 engages the teeth of the gear 162 with the teeth on arm 161 so that subsequent movement of the key 151 to rotate arm 156 in a clockwise direction permits the arm 156 to return to its normal position at a speed determined by the gear 162 and for a duration of time determined by the period which the foot pedal is depressed. Depression of the tone sustaining foot pedal without striking the key 151 produces no tone sustaining effect since the teeth on the gear 162 and arm 161 cam out of engagement because of the slot 174 (Fig. 11) in arm 163.

Although the structure of only one key 151 together with its shutter raising apparatus is shown, any desired number of units are provided in accordance with the desired number of keys 151 in the keyboard. The shaft 160 is common to all of the shutter moving assemblies as is the shaft 175 (Fig. 11) upon which a plurality of gears 162 are secured. The diameters of the gears 162 may be varied so that although a single constant speed shaft 175 is used with the multiplicity of gears 162, the speed at which the shutters 79 are returned may be varied among the several note reproducing units. Therefore, it is possible to provide relatively slow shutter return or long taper for low frequency notes while producing a fast shutter return or short tone taper for high frequency notes in addition to varying the speed of the gear.

A soft volume control is provided by a foot pedal connected to a lever 1'76 (Fig. 12) which is pivoted about a shaft 177. An arm 178 slidably connected to lever 176 is secured to an arm 179 depending from a shaft 180. A spring 181 secured to the arm 179 holds an upper end of a slot 18-2 in arm 178 in contact with a. pin 183' fastened to lever 176. Depression of the soft volume pedal rotates lever 176 about shaft 1'77 in a counter-clockwise direction so that arm 1'79 rotates in the, same direction to move shaft l'eil in a counter-clockwise direction.

An. arm 13 (Figs. 11 and i2) secured to shaft 13$ is connected to'arm through a link 135' so that counterclockwise rotation of shaft moves arm 15s) away from the arcuate portion 155. ince the arm 15%, and consequently the bar 152, are moved away from the arcuate portion 155', the bar 152 remains in interference contact with the arm 156 for a shorter period of time after depression of the key 151, and consequently the arm 156 is not moved through as great a distance as before, Since the shutter 79 is tapered in its light transmission characteristics, the decreased degree of rotation of arm 156 does not raise the shutter to the full open position of normally greater light transmission and, ac cordingly, the volume of the sound produced is not as great as before the soft volume pedal was depressed. A

compression spring 185 (Fig. 12) returns the lever 176 to its normal position and a stop bar 187 prevents excessive depression of the lever 1'76.

Depression of the soft volume lever 1.76 can also provide a sustained tone. because the shaft 16L is connected to lever 17 6 through an arm 182; secured to shaft 169 and having a slot 189 therein engaging a pin secured to 8 the lever 176. The counter-clockwise rotation of lever 176 produced by depression of the foot pedal moves the shaft 160 in a downward direction and provides a tapered tone in the manner described above.

A sustained volume control is provided by a lever 200 rotatable on a shaft 2491. The lever Ziiil is linked to an arm 199 secured to the shaft 184 by an arm 202 having a slot 203 therein through which a pin 204 secured to the lever 200 extends. Depression of the sustained volume control rotates lever 2% in a counter-clockwise direction and consequently rotates arm 199, shaft 185?, and arm 184 in a clockwise direction to move bar 152 further beneath the arcuate portion In this position, the bar 152 and arm 156 remain in striking engagement for a longer period of time and the shutter 79 is consequently raised further than in the normal position whereby a more translucent portion of the shutter 79 permits a greater intensity of light to impinge upon the cell 80 to produce a sound of greater volume. A tension spring 265 returns the lever 2% to its normal position and a stop bar 206 prevents excessive depression of the lever 2%.

Depression of the lever 2% also provides a sustained tone through movement of a flanged rocker arm 207 about a shaft 208 to move downwardly a link 209 secured to shaft 166. The sustained tones are controlled by the downward movement of shaft in the manner described above. Since the shafts 160 and are common to all of the assemblies of keys 151, the movements of any of the three foot pedals control the volume and taper of all of the tones produced by the system. Obviously, the sustaining control linkage may be removed from either one or both of the levers 176 and 200 if it is desired to produce a change in volume without sustaining the tones.

The key assemblies may be converted for use as an organ keyboard to produce tones which will not possess the tapered characteristics by moving inwardly a shaft 210 which is pivotally secured to the shaft ltiil through a link 211. This movement rotates the shaft 1% in a clockwise direction to move the arm 15d and bar 152 into contact with the right hand extremity of the arcuate portion 155 as viewed in Fig. 11. In this position, the bar 152 remains in contact with the arm 156 upon depression of the key 151i and the position of the shutter 79 is at all times dependent upon the position of the key 151.

The movement of the arm 184 into this position carries a spring 212 interconnecting the arm 1% with the arm 159 over center so that the arm 159 is prevented from following the upward movement of the key 151 and accordingly prevents engagement of the teeth on the gear 162 and arm 161 to produce a slow return and, consequently, a tapered tone.

With the foregoing description in mind it is believed that the operation of the electric organ systems will now be understood. To operate the system shown in Figs. 1, 2, and 3, the operator manually closes any desired combinations of the switches 27 to 36, inclusive, to ground a like combination of the conductors 31 to 34, inclusive, to select the musical instruments, the notes of which are to be reproduced. Following this the constant speed motor 76 is energized to rotate the plurality of spur gears 75' and consequently the plurality of cylinders 55. The rotation of the cylinders produces a plurality of beams of light of varying intensity which are all focused through the slits 78 onto the opaque portion of the tapered shutters 79.

The operator then manually depresses a desired permutation of the keys 36 in the keyboard 35 to close the same combination of switches 37 associated therewith. Assuming that the switches 27 and 34) were initially closed bythe operator, a depression of the keys 36 completes a circuit from grounded battery 38 through conductors 40,

solenoids 95, conductors 31, 34 and thence through switches 27 and 30 to ground. This circuit energizes the solenoids 95 associated with the notes selected by the depression of the keys 36 and also associated with the desired musical instruments selected by the closure of the switches 27 and 30.

The operation of these solenoids 95 pivots the arms 90 to raise the tapered shutters 79' so that the light beams produced by the rotating cylinders 55 pass through the light transmitting portion of the shutters 79 to impinge upon a plurality of the photoelectric cells 80. The resultant currents generated by the cells 80 are amplified and mixed by the amplifiers 96 and 98 and subsequently coupled to the electro-acoustical transducer 99 (Fig. 8) to produce a complex sound wave representative of the selected notes of the selected musical instruments.

When the depressed keys 36 are released by the operator the associated switches 37 are opened to break the energizing circuit of the operated relays 75 so that the arms 90 are rotated in a clockwise direction by the action of the springs 92 so that the opaque portions of the shutters 79 are once again interposed between the slits 78 and the photoelectric cells 80. Because of the tapered light transmission characteristic of the shutters 79, the magnitude of the light reaching the photoelectric cells 80 following the release of the keys 36 is gradually decreased to produce a tapered tone. Obviously the tension produced by the spring 92 may be varied to produce the desired speed of return of the arm 90, or the spring 92 may be replaced by any of the well known equivalents such as the dash pot or pneumatic solenoid, the speed of operation of which may be easily adjusted to produce the desired degree of tone taper. The circuit is now in condition for operation in a cycle similar to that described above. Obviously any new combination of the switches 27 to 30, inclusive, may be operated to provide a new tone mixture produced by the reproduction of notes of a diflerent combination of musical instruments.

The electric organ system shown in Figs. 4, 5, and 6 is placed in operation by the manual operation of a desired combination of the switches 113 to 116, inclusive. Assuming that the switches 113 and 116 are closed by the operator, all of the relays 131 associated with the desired instruments in each of the reproducing units 100 to 106, inclusive, are operated by an energizing circuit comprising grounded battery 107, conductor 108, the operating windings of the relays 131, conductors 109, 112 and thence through operated switches 113 and 116 to ground. The energization of these solenoids 131 produces a flux field which attracts and holds the soft arm slugs 132 associated with the energized solenoids whereby the fingered plates 133 are magnetically clutched to certain of the arms 118.

The operator then depresses the desired combination of the keys 117 so that the lever arms 136 are rotated in a clockwise direction and consequently the plates 133 rotated in a counter-clockwise direction to elevate the pivoted arms 118 which have been previously magnetically clutched to predetermined fingers of the plates 133. This movement of the arms 118 moves the opaque portions of the shutters 79 out of alignment with the slits 78 so that beams of light representative of the selected musical notes of the selected musical instruments impinge upon the photoelectric cells 80 to produce electrical currents of varying amplitude. These currents are subsequently amplified and coupled to the transducer 99 to produce a complex sound wave including the musical notes of the selected musical instruments.

Release of the depressed keys 117 allows the springs 120 to rotate the arms 118 in a clockwise direction about the shaft 119 so that the opaque portions of the shutters 79 are once again interposed between the photoelectric cells 80 and the light beams of varying intensity. Obviously, the rate of return of the shutters 79 to their normal position is governed by the rate at which the operator permits the return of the keys 117 to their normal position and,

accordingly the degree of tapered tone produced by the greater light transmission characteristic of the shutter 79 is in the direct control of the operator. When the keys 117 are all released to their normal position the keyboard is conditioned for operation in a manner identical to that described above. Obviously any new desired combination of the switches 113 to 116 inclusive may be operated when it is desired to vary the combination of musical instruments to be included in the complex sound wave produced by the transducer 99.

The operation of the systems shown in Figs. 1 to 6, inclusive, utilizing the gearing modification shown in Fig. 10 is identical to that described above, except that the cylinders 55 are operated at different speeds to produce the light beams of varying intensity.

The modification disclosed in Fig. 7 of the drawings also operates in the same manner described above with the exception that the light beams of varying intensity are optically combined to produce a composite light beam bearing the desired modulation intelligence. In this modification, the output of the single photoelectric cell is amplified and coupled to the transducer 99 to produce a complex sound wave.

The modification shown in Figs. 11 and 12 replaces the electrical (Figs. 1, 2 and 3) and electromechanical (Figs. 4, 5 and 6) apparatus for moving the shutters 79, but the remainder of the reproduction system operates as described above.

The above described modifications are merely illustrative of the principles of the invention and numerous other embodiments may be devised by those skilled in the art which will fall within the spirit and scope of this invention.

What is claimed is:

1. A system for producing a compound sound wave including a plurality of different complex sound waves of musical instruments comprising means for producing a plurality of light beams, each of said light beams varying in intensity in accordance with characteristics of a different musical instrument sound wave, means normally occupying a resting position for interrupting said beams selectively including an element for each beam of varying translucency, light responsive means energized by light beams selected by said elements to produce a compound sound Wave including the sound waves of the light beams energizing the responsive means, means including finger actuated keys momentarily engaging said interrupting means to drive said interrupting means from their respective resting positions when moved in one direction for varying the positions of said elements to vary the magnitude of the intensity of the light beams energizing the responsive means to produce a compound sound wave of predetermined content, means for restoring said elements to beam interrupting positions at a predetermined speed to taper the compound sound proportionally throughout the range of its components including a continuously rotating member engaged by said interrupting means when driven from said resting positions and means controlled by said key for interrupting said engagement by said interrupting means when the key is moved in the opposite direction.

2. A device for producing a tapered musical tone comprising means for producing a light beam of complex wave form representative of a musical sound of a musical instrument, a light responsive means positioned to be energized by the light beam to generate a complex sound wave, a shutter interposed between the light beam and the responsive means, said shutter being gradually tapered from opaque to transparency with the opaque portion normally intercepting the light beam, means secured to the shutter for moving the shutter relative to the beam, means including a key for engaging said received means for quickly moving said secured means so that the light beam energizes the responsive means through the transparent portion substantially instantly when the key is depressed, and means including a unidirectional rotating element engaged by said secured means while said key is depressed for returning the shutter to its position at a predetermined rate whereby a gradually tapered musical tone is produced by the responsive means corresponding to the musical sound made by the musical instrument when played.

3. A device for producing a tapered musical tone comprising means for producing a light beam of complex wave form representative of a musical sound of a musical instrument, a light responsive means positioned to be energized by the light beam to generate a complex sound wave, a shutter interposed between the light beam and the responsive means, said shutter being gradually tapered from opaque to transparency with the opaque portion normally intercepting the light beam, means secured to the shutter for moving the shutter relative to the beam, means including a key for engaging said secured means for quickly moving said secured means so that the light beam energizes the responsive means through the transparent portion substantially instantly when the key is depressed, means including a unidirectional moving element engaged by said secured means while said key is depressed for returning the shutter to its position at a predetermined rate whereby a gradually tapered musical tone is produced by the responsive means corresponding to the musical sound made by the musical instrument when played, and means controlled by said key means for releasing said engagement by said secured means for quickly returning the shutter when said key is released.

4. A device for producing a tapered musical tone comprising means for producing a light beam of complex wave form representative of a musical sound of a musical instrument, a light responsive means positioned to be energized by the light beam to generate a complex sound wave, a shutter interposed between the light beam and the responsive means, said shutter being gradually tapered from opaque to transparency with the opaque portion normally intercepting the light beam, means secured to the shutter for moving the shutter relative to the beam quickly so that the light beam energizes the responsive means through the transparent portion substantially instantly with the movement of the shutter, and means for returning the shutter to its position at a predetermined rate whereby a gradually tapered musical tone is produced by the responsive means corresponding to the musical sound made by the musical instrument when played, said means for returning the shutter including a rotating shaft, an element pivotally mounted on the shaft to control the shutter, and a gear and rack assembly interconnecting said shaft and element in unidirectional drive relationship.

5. A. device for producing a tapered musical tone comprising means'for producing a light beam recorded from a musical tone produced by a musical instrument when played, a light responsive means positioned to be energized by the beam for generating a complex sound wave, a shutter interposed between the light beam and the responsive means, said shutter having a gradually varying light transmission characteristic with an opaque portion thereof normally intercepting the light beam, means secured to the shutter for moving said shutter, means including a key for momentarily striking said secured means when the key is depressed for driving said secured means from its resting position to move the shutter a variable distance quickly relative to the responsive means to energize said responsive means through a transparent portion of said shutter, a timing means including a rotatable shaft, and normally idle means controlled by said key when depressed for interconnecting the timing means and the moving means for returning the opaque portion of the shutter to its normal position at a pre-.

determined speed.

6. in combination with a means for producing a light beam representative of a musical tone, a light responsive means positioned so as to be energized by the light beam,

a shutter interposed between the light beam and the responsive means having a gradually varying light transmissivity, and means for moving the shutter comprising a first member secured to the shutter and movable along a predetermined path, a second member movable along another predetermined path in overlapping relation with a portion of the first path and having a momentary driving engagement with the first member in said overlapping portion of said path to move the shutter quickly relative to the responsive means varying distances through the range or" varying light transmissivity, means engaging one of said members for adjusting the duration of the driving engagement, timing means, and means controlled by the movement of the second member for engaging the timing means with the first member to return the shutter to its original position at a predetermined speed through its range of varying light transmissivity.

7. A system for producing a variable sound Wave comprising means for producing a plurality of light beams of complex varying intensity each representative of a plurality of different sounds of a musical instrument, a plurality of light responsive means for generating a composite sound wave, each of said responsive means positioned so as to be energized by one of the light beams, a plurality of shutters interposed between the responsive means and the light beams, said shutters having an opaque portion normally in alignment with the light beams and being gradually tapered to transparency, means including manually actuated keys for selectively moving a predetermined number of the shutters to a position with the transparent portion thereof in alignment with the light beam when the keys are depressed so that the selected number of responsive means are energized with light variations of an increased intensity to produce a composite sound Wave, timing means including a shaft revolving constantly in one direction engaged by said shutters for returning the shutters to their normal positions independently and collectively at the same speed while said keys are depressed to impose upon said composite sound wave a tone taper corresponding to the tone taper of said musical instrument of gradually decreasing intensity.

8. A system for producing a variable sound wave comprising means for producing a plurality of light beams of complex varying intensity each representative of a plurality of different sounds of a musical instrument, a plurality of light responsive means for generating a composite sound wave, each of said responsive means positioned so as to be energized by one of the light beams, a plurality of shutters interposed between the responsive means and the light beams, said shutters having an opaque portion normally in alignment with the light beams and being gradually tapered to transparency, means including manually actuated keys for selectively moving a predetermined number of the shutters to a position with the transparent portion thereof in alignment with the light beam when the keys are depressed so that the selected number of responsive means are energized with light variations of an increased intensity to produce a composite sound Wave, timing means including a shaft revolving constantly in one direction engaged .by said shutters for returning the shutters to their .normal positions independently and collectively at the same speed While said keys are depressed to impose upon said composite sound wave a tone taper corresponding to the tone taper of said musical instrument of gradually decreasing intensity, and means for disengaging said shutters from said timing means when said keys are released to accelerate their return to normal position.

9. A system for producing a variable sound wave comprising means for producing a plurality of light beams representative of the notes of a plurality of musical in-- struments, light responsive means for generating a composite sound wave upon energi z'ation by the light beams, a plurality of shutters interposed between the light beams and the responsive means, each of said shutters having an opaque portion normally preventing incidence of the beams on the response means and being gradually tapered to transparency, means supporting said shutters for movement edgewise with respect to said beams, a plurality of keys representing the notes of the musical range of the instruments, means driven by said keys when depressed for momentarily engaging said supporting means selectively in driving relationship to move said supporting means to carry the shutters intercepting selected beams representing notes of a desired number of the plurality of instruments with the plurality of keys and move transparent portion of the shutters associated with the selected instruments and notes into alignment with the light beams to energize the responsive means for generating a composite sound Wave including the desired notes of the selected instruments, and means for tapering the intensity of said notes including a continuously moving member engaged by said supporting means for gradually returning said shutters to their resting positions cooperatively independently of said driven means while said keys depressed and means actuated by sai keys for releasing said engagement by said supporting means when said keys are released.

10. The combination called for in claim 6 including resilient means carried by one of said members to permit one of said members to pass the other member in said overlapping portion of said path when the one member is moving in a direction opposite said driving engagement movement.

11. The combination called for in claim 6 in which said means for adjusting the duration of the driving engagement includes a manually-operated pedal.

12. In combination with a means for producing a light beam representative of a musical sound, light responsive means positioned to be energized by the light beam, beam interrupting means including an element having a gradually varying light transmissivity with a portion thereof of least transmissivity normally intercepting the light beam, means engaging said beam interrupting means including a manually-actuated key element for driving said element to a second position in which a portion thereof of greatest light transmissivity lies in the path of the light beam, timing means, means controlled by said key for engaging said beam interrupting means with said timing means while said key is depressed for timing the return of said element to its resting position through its range of varying light transmissivity, and means controlled by said engaging means for releasing said engagement when said keyelement is released for returning said element immediately to its resting position.

13. The combination called for in claim 10 including means for removing said controlled means from operation when said key is released including a second manuallyoperated element.

14. The combination called for in claim 9 in which said engagement between said key-controlled means and beaminterrupting means comprises one-way clutch elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,819,820 Kent Aug. 18, 1931 1,848,222 Potter Mar. 8, 1932 1,937,021 Hammond Nov. 28, 1933 1,948,996 Toulon Feb. 27, 1934 1,998,461 Kucher Apr. 23, 1935 2,031,764 Eremeeff Feb. 25, 1936 2,169,842 Kannenburg Aug. 15, 1939 2,376,493 Land et al May 22, 1945 2,539,130 Grudin Ian. 23, 1951 2,586,664 Knoblaugh Feb. 19, 1952 FOREIGN PATENTS 822,752 Germany Nov. 29, 1951 

